The present invention relates to asphalt plants and especially to batch type asphalt plants to which an asphalt recycling system is added for utilizing old asphaltic pavement materials, and the like, to produce high quality new paving materials.
In the past, asphalt plants have generally been of two types, one being of the type where the aggregate is dried and mixed with the liquid bitumen in the dryer and the other being a batch type where the liquid bitumen is mixed with the aggregate later in the mixer crimping mill. Batch type plants typically have hopper feeds for feeding different size cold aggregate materials by means of a cold feed conveyor into the dryer. The dryer typically involves a large elongated drum having a burner directed into one end, with the aggregate being fed therethrough from the other end, and providing rotation of the drum with flights for mixing the aggregate material with the hot gases and causing it to be dried. As the material passes through the drum, the hot air and gases from the burner pass out the other end of the dryer into a ducting system which is directed towards a wet wash, mechanical collector, or fabric filter dust collector for cleaning the air and gases prior to their discharge from a stack. Meanwhile, the dried aggregate materials are fed up a slat type hot elevator to a batching tower, where the material is passed through screens for separating it into sizes and asphalt liquid from an asphalt storage tank is fed into the weigh box or mixer at the bottom of the tower, along with mineral fillers and mixed with the aggregate prior to loading into a truck.
Entire plants are typically controlled by a control room having the plant controls. This type of plant has been commonly used around the world, but has the disadvantage of not being able to process old, used asphaltic pavement materials. The present invention is specifically directed to add to an existing batch type asphalt plant a used asphalt recycle plant utilizing the waste heated air and gases from the existing batch type plant, as well as the existing filter system, and being controlled to provide additional heated gases as needed along with controls for cutting in the recycling plant as needed.
It is accordingly, an aim of the present invention to recycle existing asphalt materials utilizing waste heat and other components of an existing batch type asphalt type plant.